Before he enter on the Execution of his Office, he shall take the following Oath or Affirmation:—"I do solemnly swear (or affirm) that I will faithfully execute the Office of President of the United States, and will to the best of my ability, preserve, protect and defend the Constitution of the United States."[1]

This clause is one of several that employ the oath concept, but it is the only clause that actually specifies the language of an oath for a constitutional officer. While the Oaths Clause in Article VI simply requires the persons specified therein to "be bound by oath or affirmation, to support this Constitution," the Presidential Oath Clause requires much more than this general oath of allegiance and fidelity. This clause enjoins the President to swear or affirm that he "will to the best of [his] Ability, preserve, protect and defend the Constitution of the United States."[2]

The Constitutional language gives the option to "affirm" instead of "swear". While the reasons for this are not documented, it may relate to certain Christians, including Quakers, who apply this scripture literally: "But above all things, my brethren, swear not, neither by heaven, neither by the earth, neither by any other oath: but let your yea be yea; and your nay, nay; lest ye fall into condemnation" (James 5:12, KJV).[8]Franklin Pierce was the only president known to use the word "affirm" rather than "swear." Herbert Hoover is often listed to have used "affirm" as well, owing to his being a Quaker, but a newsreel taken of the ceremony indicates that the words used were "solemnly swear."[9] Richard Nixon, who was also a Quaker, also swore, rather than affirm.[10][11]

There have been two forms of administering, and taking, the oath of office.

Under the first form, now in disuse, the administrator articulated the constitutional oath in the form of a question, and modifying the wording from the first to the second person, as in, "Do you George Washington solemnly swear ..." and then requested an affirmation. At that point a response of "I do" or "I swear" completed the oath.[citation needed]

It is believed that this was the common procedure at least until the early 20th century. In 1881, the New York Times article covering the swearing in of Chester A. Arthur, reported that he responded to the question of accepting the oath with the words, "I will, so help me God."[12] In 1929, Time magazine reported that the Chief Justice began the oath uttering, "You, Herbert Hoover, do you solemnly swear ...",[13] Hoover replied with a simple "I do".[14]

Under the second, and current form, the administrator articulates the oath in the affirmative, and in the first person, so that the President takes the oath by repeating it verbatim.[citation needed] Franklin Roosevelt, in 1933, stood silent as Chief Justice Charles Evans Hughes recited the entire oath, then repeated that oath from beginning to end himself.[15] By the time of Harry Truman's inauguration in 1949, the practice was for the Chief Justice to utter the oath in chunks, with the President-elect repeating those chunks, until the oath was completed.[16]

Many times the President-elect's name is added after the "I"; for example, "I, Franklin D. Roosevelt, do ... " Lyndon B. Johnson did not add his name when swearing his first oath of office after Kennedy's death since he was never asked to say his name; there is evidence that in all other inaugurations since Franklin D. Roosevelt's first, the name of the president was added to the oath.[citation needed]

It is uncertain how many Presidents used a Bible or added the words "So help me God" at the end of the oath, or in their acceptance of the oath, as neither is required by law; unlike many other federal oaths which do include the phrase "So help me God."[25] There is currently debate as to whether or not George Washington, the first president, added the phrase to his acceptance of the oath. No contemporary sources mention Washington as adding a religious codicil to his acceptance.[26]

The historical debate over who first used "So help me God," is marred by ignoring the two forms of giving the oath. The first, now in disuse, is when the administrator articulates the constitutional oath in the form of a question, as in, "Do you George Washington solemnly swear...", requesting an affirmation. At that point a response of "I do" or "I swear" completes the oath. Without verbatim transcripts, the scant existing evidence shows this was the common procedure at least until the early 20th century. In 1865 the Sacramento Daily Union covered the second inauguration of Abraham Lincoln. Lincoln finished his oath with "So help me God," and he kissed the bible.[27] In 1881, the New York Times article covering the swearing in of Chester A. Arthur, reported that he responded to the question of accepting the oath with the words, "I will, so help me God".[12] In 1929, Time magazine reported that the Chief Justice began the oath uttering, "You, Herbert Hoover, do you solemnly swear..."[13] Hoover replied with a simple "I do".

A Federal lawsuit filed in the District of Columbia by Michael Newdow on December 30, 2008 contended the second, current form of administration, where both the Chief Justice and the President articulate the oath, appending "So help me God", to be a breach of the Constitutional instructions. The suit distinguishes between the words spoken by the administrator, which must conform to the exact 35 words of the Constitution, and the President, who has a right to add a personal prayer, such as "So help me God."[28]

Chief Justice Roberts' reply was that his "prompting" for these four extra-constitutional words were to be recited "after" the oath of office, and not as a part of the oath as claimed in the suit. After rendering the oath to President Barack Obama, Roberts prompted with a question "So help you God?", to which the President responded, "So help me God."[29]

The first Congress explicitly prescribed the phrase "So help me God" in oaths under the Judiciary Act of 1789 for all U.S. judges and officers other than the President. It was prescribed even earlier under the various first state constitutions[30] as well as by the Second Continental Congress in 1776.[31][32] Although the phrase is mandatory in these oaths, the said Act also allows for the option that the phrase be omitted by the officer, in which case it would be called an affirmation instead of an oath: "Which words, so help me God, shall be omitted in all cases where an affirmation is admitted instead of an oath."[33] In contrast, the oath of the President is the only oath specified in the Constitution. It does not include the closing phrase "So help me God", and it also allows for the optional form of an affirmation which is not considered an oath. In practice, however, most Presidents, at least during the last century, have opted to take the oath (rather than an affirmation), to use a Bible to do so, and also to close the oath with the customary phrase.

The earliest known source indicating Washington added "So help me God" to his acceptance, not to the oath, is attributed to Washington Irving, aged six at the time of the inauguration, and first appears 65 years after the event.[34]

The only contemporary account that repeats the oath in full, a report from the French consul, Comte de Moustier, states only the constitutional oath,[35] without reference to Washington's adding "So Help Me God" to his acceptance.

Evidence is lacking to support the claim that Presidents between Washington and Abraham Lincoln used the phrase "So help me God." A contemporaneous newspaper account of Lincoln's 1865 inauguration states that Lincoln appended the phrase "So help me God" to the oath.[36] This newspaper report is followed by another account, provided later in the same year after Lincoln's death (April 15, 1865), that Lincoln said "So help me God" during his oath.[37] The evidence pertaining to the 1865 inauguration is much stronger than that pertaining to Lincoln's 1861 use of the phrase. Several sources claim that Lincoln said "So help me God" at his 1861 inauguration, yet these sources were not contemporaneous to the event.[38][39] During the speech, Lincoln stated that his oath was "registered in Heaven",[40] something some have taken as indicating he likely uttered the phrase "So help me God." Conversely, there was a claim made by A.M. Milligan (a Presbyterian minister who advocated for an official Christian U.S. government) that letters were sent to Abraham Lincoln asking him to swear to God during his inaugurations, and Lincoln allegedly wrote back saying that God's name was not in the Constitution, and he could not depart from the letter of that instrument.[41][42]

Other than the president of the U.S., many politicians (including Jefferson Davis, sworn in as president of the Confederate States of America in 1861) used the phrase "So help me God" when taking their oaths.[43] Likewise, all federal judges and executive officers were required as early as 1789 by statute to include the phrase unless they affirmed, in which case the phrase must be omitted.[44]

Given that nearly every President-elect since President Franklin D. Roosevelt has recited the codicil, it is likely that the majority of presidents-elect have uttered the phrase[45] (as well as some vice presidents, while taking their oaths). However, as President Theodore Roosevelt chose to conclude his oath with the phrase "And thus I swear," it seems that this current of tradition was not overwhelmingly strong even as recently as the turn of the twentieth century. Only Franklin Pierce has chosen to affirm rather than swear.[46] It is often asserted that Herbert Hoover also affirmed, because he was a Quaker, but newspaper reports before his inauguration state his intention to swear rather than affirm.[47]

President Barack Obama being administered the oath of office by Chief Justice John Roberts for the second time, on January 21, 2009.

In 1909, when President William Howard Taft was sworn in, Chief JusticeMelville Fuller misquoted the oath, but the error was not publicized at the time. The mistake was similar to the one Taft himself would make twenty years later when swearing in President Hoover. Recalling the incident, Taft wrote, "When I was sworn in as President by Chief Justice Fuller, he made a similar slip," and added, "but in those days when there was no radio, it was observed only in the Senate chamber where I took the oath."[13]

In 1929, Taft, later the Chief Justice, garbled the oath when he swore in President Herbert Hoover using the words "preserve, maintain, and defend the Constitution", instead of "preserve, protect, and defend". The error was picked up by schoolgirl Helen Terwilliger on the radio. Taft eventually acknowledged his error, but did not think it was important, and Hoover did not retake the oath. In Taft's view, his departure from the text did not invalidate the oath.[13][48][49]

In 1945, President Harry S. Truman's bare initial caused an unusual slip when he first became president and took the oath. At a meeting in the Cabinet Room, Chief JusticeHarlan Stone, apparently mistaken about the meaning of Truman's middle initial (which is not an abbreviation but rather the whole middle name in itself), began reading the oath by saying "I, Harry Shipp Truman...", Truman responded: "I, Harry S Truman,..."[50]

In 1965, Chief Justice Earl Warren prompted Lyndon Johnson to say, "the Office of the Presidency of the United States".[51]

In 2009, Chief Justice John G. Roberts, while administering the oath to Barack Obama, incorrectly recited part of the oath. Roberts prompted, "That I will execute the Office of President to the United States faithfully." Obama stopped at "execute," and waited for Roberts to correct himself. Roberts, after a false start, then followed Obama's "execute" with "faithfully", which results in "execute faithfully," which is also incorrect. Obama then repeated Roberts' initial, incorrect prompt, with the word "faithfully" after "United States."[52][53] The oath was re-administered the next day by Roberts at the White House.[54][55]

From 1789 through 2013, the presidential oath of office has been administered by 15 Chief Justices, one Associate Justice, three federal judges, two New York state judges, and one notary public. The oath has been taken on 73 occasions by 43 people; seven have repeated their oath of office (for differing reasons).

^Chief Justice Roberts administered the presidential oath a second time to Barack Obama "out of an abundance of caution," according to the White House, because, when the oath was administered the first time in the public inauguration ceremony, the word "faithfully" was misplaced.[68]

^On January 21, 2013, Barack Obama became the second president to take the oath of office four times.[65]

Map showing locations where the oath of office was first taken, marked with a green 'O' (or a green dot for normal transitions). Locations where presidencies ended are marked with a red 'X' (or a red dot for normal transitions). The nine sets of names shown in black are the ones in which transition took place prior to completion of the term, with four due to death by illness, four due to assassination (names underlined in grey), and one resignation (noted by a superscript 'R'). Inset at the bottom of the map is a crop from the Constitution (see full page) that specifies the oath.

^McCullough, David (1992). Truman. New York: Simon and Schuster. pp. 347, p. 729. ISBN0-671-86920-5. Harry Truman is a notable example, as he bent and kissed the Bible upon taking the oath for the first time, on April 12, 1945, as well as at his second inauguration.

^"Case 1:08-cv-02248-RBW Document 13-9"(PDF). www.restorethepledge.com. 2009-01-08. p. 25. Retrieved 2009-02-04. Before the commencement of this lawsuit, the Chief Justice instructed me to ascertain from President-Elect Obama's representatives the President-Elect's wishes concerning the administration of the oath of office at the inauguration~including his wishes concerning the inclusion of the phrase "So help me God" after the conclusion of the constitutional oath

^Foster, James Mitchell (1894) [1894]. Christ the King. Boston: James H. Earle. p. 277. In fact, Milligan did write to Lincoln, but his request was not that Lincoln add "so help me God" to the Oath, but rather that the name of Jesus Christ be added to the U.S. Constitution [1]